In some situations it is desirable to provide a polymeric composition that contains both a polymer and a multivalent cation. One example of such a situation is one in which it is desired to coagulate a polymer latex, for example as part of a process of separating the polymer of the latex from the water of the latex. Two common ways of performing such separation are coagulation and spray drying. Coagulation has the advantage that the equipment required to perform coagulation requires less capital expense than the equipment required to perform spray drying. Coagulation has the disadvantage that the coagulation process normally introduces multivalent cations into the solid polymer. In some cases, the presence of a multivalent cation in a polymer composition is a drawback. For example, if the polymer composition is used as an additive in a matrix resin, the multivalent cation sometimes causes deleterious effects on the matrix resin.
U.S. Pat. No. 5,290,867 discloses producing an emulsion graft copolymer, coagulating that graft copolymer with an alkaline earth metal compound, and then using that graft copolymer for reinforcing natural rubber, for modifying rubber-based adhesives, or in fibers or films.
It is desired to provide polymer compositions that contain multivalent cation and that reduce or eliminate the drawbacks that normally occur when a multivalent cation is present in a polymer composition. Such a desired composition would have various benefits. For example, such a desired composition, when used as an additive to a matrix resin, would reduce or eliminate the deleterious effects on the matrix resin that would have been caused by a previously-known additive with a similar level of multivalent cation.
In one particular example, it is desired to produce a polymer as part of a polymer latex; to separate that polymer from the water of the latex; and to use the separated polymer as an additive in a matrix resin. Using previously-known methods, there would be a choice: either (1) incurring relatively high expense by separating the polymer from the water of the latex by spray drying, or (2) introducing deleterious multivalent cations by separating the polymer from the water of the latex by coagulation. In this particular example, it is desired to provide a method of reducing or eliminating the deleterious effects of the multivalent cation, because the use of such a method would allow a coagulated polymer to be used as an additive to a matrix resin without causing the deleterious effects from the multivalent cation that would otherwise have occurred.